﻿// Copyright (c) 2018, Rene Lergner - wpinternals.net - @Heathcliff74xda
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.

// These functions assume same endianness for the CPU architecture and the raw data it reads from or writes to.

using System;
using System.IO;

namespace WPinternals
{
    internal static class ByteOperations
    {
        internal static string ReadAsciiString(byte[] ByteArray, UInt32 Offset, UInt32 Length)
        {
            byte[] Bytes = new byte[Length];
            Buffer.BlockCopy(ByteArray, (int)Offset, Bytes, 0, (int)Length);
            return System.Text.Encoding.ASCII.GetString(Bytes);
        }

        internal static string ReadUnicodeString(byte[] ByteArray, UInt32 Offset, UInt32 Length)
        {
            byte[] Bytes = new byte[Length];
            Buffer.BlockCopy(ByteArray, (int)Offset, Bytes, 0, (int)Length);
            return System.Text.Encoding.Unicode.GetString(Bytes);
        }

        internal static void WriteAsciiString(byte[] ByteArray, UInt32 Offset, string Text, UInt32? MaxBufferLength = null)
        {
            if (MaxBufferLength != null)
                Array.Clear(ByteArray, (int)Offset, (int)MaxBufferLength);

            byte[] TextBytes = System.Text.ASCIIEncoding.ASCII.GetBytes(Text);
            int WriteLength = TextBytes.Length;
            if (WriteLength > MaxBufferLength)
                WriteLength = (int)MaxBufferLength;

            Buffer.BlockCopy(TextBytes, 0, ByteArray, (int)Offset, WriteLength);
        }

        internal static void WriteUnicodeString(byte[] ByteArray, UInt32 Offset, string Text, UInt32? MaxBufferLength = null)
        {
            if (MaxBufferLength != null)
                Array.Clear(ByteArray, (int)Offset, (int)MaxBufferLength);

            byte[] TextBytes = System.Text.UnicodeEncoding.Unicode.GetBytes(Text);
            int WriteLength = TextBytes.Length;
            if (WriteLength > MaxBufferLength)
                WriteLength = (int)MaxBufferLength;

            Buffer.BlockCopy(TextBytes, 0, ByteArray, (int)Offset, WriteLength);
        }

        internal static UInt32 ReadUInt32(byte[] ByteArray, UInt32 Offset)
        {
            return BitConverter.ToUInt32(ByteArray, (int)Offset);
        }

        internal static void WriteUInt32(byte[] ByteArray, UInt32 Offset, UInt32 Value)
        {
            System.Buffer.BlockCopy(BitConverter.GetBytes(Value), 0, ByteArray, (int)Offset, 4);
        }

        internal static Int32 ReadInt32(byte[] ByteArray, UInt32 Offset)
        {
            return BitConverter.ToInt32(ByteArray, (int)Offset);
        }

        internal static void WriteInt32(byte[] ByteArray, UInt32 Offset, Int32 Value)
        {
            System.Buffer.BlockCopy(BitConverter.GetBytes(Value), 0, ByteArray, (int)Offset, 4);
        }

        internal static UInt16 ReadUInt16(byte[] ByteArray, UInt32 Offset)
        {
            return BitConverter.ToUInt16(ByteArray, (int)Offset);
        }

        internal static void WriteUInt16(byte[] ByteArray, UInt32 Offset, UInt16 Value)
        {
            System.Buffer.BlockCopy(BitConverter.GetBytes(Value), 0, ByteArray, (int)Offset, 2);
        }

        internal static Int16 ReadInt16(byte[] ByteArray, UInt32 Offset)
        {
            return BitConverter.ToInt16(ByteArray, (int)Offset);
        }

        internal static void WriteInt16(byte[] ByteArray, UInt32 Offset, Int16 Value)
        {
            System.Buffer.BlockCopy(BitConverter.GetBytes(Value), 0, ByteArray, (int)Offset, 2);
        }

        internal static byte ReadUInt8(byte[] ByteArray, UInt32 Offset)
        {
            return ByteArray[Offset];
        }

        internal static void WriteUInt8(byte[] ByteArray, UInt32 Offset, byte Value)
        {
            ByteArray[Offset] = Value;
        }

        internal static UInt32 ReadUInt24(byte[] ByteArray, UInt32 Offset)
        {
            return (UInt32)(ByteArray[Offset] + (ByteArray[Offset + 1] << 8) + (ByteArray[Offset + 2] << 16));
        }

        internal static void WriteUInt24(byte[] ByteArray, UInt32 Offset, UInt32 Value)
        {
            System.Buffer.BlockCopy(BitConverter.GetBytes(Value), 0, ByteArray, (int)Offset, 3);
        }

        internal static UInt64 ReadUInt64(byte[] ByteArray, UInt32 Offset)
        {
            return BitConverter.ToUInt64(ByteArray, (int)Offset);
        }

        internal static void WriteUInt64(byte[] ByteArray, UInt32 Offset, UInt64 Value)
        {
            System.Buffer.BlockCopy(BitConverter.GetBytes(Value), 0, ByteArray, (int)Offset, 8);
        }

        internal static Guid ReadGuid(byte[] ByteArray, UInt32 Offset)
        {
            byte[] GuidBuffer = new byte[0x10];
            Buffer.BlockCopy(ByteArray, (int)Offset, GuidBuffer, 0, 0x10);
            return new Guid(GuidBuffer);
        }

        internal static void WriteGuid(byte[] ByteArray, UInt32 Offset, Guid Value)
        {
            Buffer.BlockCopy(Value.ToByteArray(), 0, ByteArray, (int)Offset, 0x10);
        }

        internal static UInt32 Align(UInt32 Base, UInt32 Offset, UInt32 Alignment)
        {
            if (((Offset - Base) % Alignment) == 0)
                return Offset;
            else
                return ((((Offset - Base) / Alignment) + 1) * Alignment) + Base;
        }

        internal static UInt32? FindPatternInFile(string FileName, byte[] Pattern, byte[] Mask, out byte[] OutPattern)
        {
            // The mask is optional.
            // In the mask 0x00 means the value must match, and 0xFF means that this position is a wildcard.

            UInt32? Result = null;

            FileStream Stream = new FileStream(FileName, FileMode.Open, FileAccess.Read);

            byte[] Buffer = new byte[0x10000 + Pattern.Length - 1];
            UInt32 BufferReadPosition = 0; // Position in buffer where file-chunk is being read.
            UInt32 BytesInBuffer = 0;
            UInt32 BytesRead;
            UInt32 SearchPositionFile = 0;
            UInt32 SearchPositionBuffer = 0;
            UInt32 BufferFileOffset = 0; // Offset in file where data from buffer is located.
            bool Match = false;
            int i;

            OutPattern = null;

            while (SearchPositionFile <= (Stream.Length - Pattern.Length))
            {
                if ((SearchPositionBuffer + Pattern.Length) > BytesInBuffer)
                {
                    // Need to read next chunk
                    if ((BytesInBuffer - SearchPositionBuffer) > 0)
                    {
                        System.Buffer.BlockCopy(Buffer, (int)SearchPositionBuffer, Buffer, 0, (int)(BytesInBuffer - SearchPositionBuffer));
                    }
                    BufferReadPosition = BytesInBuffer - SearchPositionBuffer;
                    BytesInBuffer -= SearchPositionBuffer;
                    BufferFileOffset += SearchPositionBuffer;
                    SearchPositionBuffer = 0;

                    BytesRead = (UInt32)Stream.Read(Buffer, (int)BufferReadPosition, Buffer.Length - (int)BufferReadPosition);
                    BytesInBuffer += BytesRead;
                }

                Match = true;
                for (i = 0; i < Pattern.Length; i++)
                {
                    if (Buffer[SearchPositionBuffer + i] != Pattern[i])
                        if ((Mask == null) || (Mask[i] == 0))
                        {
                            Match = false;
                            break;
                        }
                }

                if (Match)
                {
                    Result = SearchPositionFile;

                    OutPattern = new byte[Pattern.Length];
                    System.Buffer.BlockCopy(Buffer, (int)SearchPositionBuffer, OutPattern, 0, Pattern.Length);
                    break;
                }

                SearchPositionBuffer++;
                SearchPositionFile++;
            }

            Stream.Close();

            return Result;
        }

        internal static UInt32? FindAscii(byte[] SourceBuffer, string Pattern)
        {
            return FindPattern(SourceBuffer, System.Text.ASCIIEncoding.ASCII.GetBytes((string)Pattern), null, null);
        }

        internal static UInt32? FindUnicode(byte[] SourceBuffer, string Pattern)
        {
            return FindPattern(SourceBuffer, System.Text.UnicodeEncoding.Unicode.GetBytes((string)Pattern), null, null);
        }

        internal static UInt32? FindUint(byte[] SourceBuffer, UInt32 Pattern)
        {
            return FindPattern(SourceBuffer, BitConverter.GetBytes((UInt32)Pattern), null, null);
        }

        internal static UInt32? FindPattern(byte[] SourceBuffer, byte[] Pattern, byte[] Mask, byte[] OutPattern)
        {
            return FindPattern(SourceBuffer, 0, null, Pattern, Mask, OutPattern);
        }

        internal static bool Compare(byte[] Array1, byte[] Array2)
        {
            return System.Collections.StructuralComparisons.StructuralEqualityComparer.Equals(Array1, Array2);
        }

        internal static UInt32? FindPattern(byte[] SourceBuffer, uint SourceOffset, uint? SourceSize, byte[] Pattern, byte[] Mask, byte[] OutPattern)
        {
            // The mask is optional.
            // In the mask 0x00 means the value must match, and 0xFF means that this position is a wildcard.

            UInt32? Result = null;

            UInt32 SearchPosition = SourceOffset;
            bool Match = false;
            int i;

            while ((SearchPosition <= (SourceBuffer.Length - Pattern.Length)) && ((SourceSize == null) || (SearchPosition <= (SourceOffset + SourceSize - Pattern.Length))))
            {
                Match = true;
                for (i = 0; i < Pattern.Length; i++)
                {
                    if (SourceBuffer[SearchPosition + i] != Pattern[i])
                        if ((Mask == null) || (Mask[i] == 0))
                        {
                            Match = false;
                            break;
                        }
                }

                if (Match)
                {
                    Result = SearchPosition;

                    if (OutPattern != null)
                        System.Buffer.BlockCopy(SourceBuffer, (int)SearchPosition, OutPattern, 0, Pattern.Length);
                    break;
                }

                SearchPosition++;
            }

            return Result;
        }

        internal static byte CalculateChecksum8(byte[] Buffer, UInt32 Offset, UInt32 Size)
        {
            byte Checksum = 0;

            for (UInt32 i = Offset; i < (Offset + Size); i++)
                Checksum += Buffer[i];

            return (byte)(0x100 - Checksum);
        }

        internal static UInt16 CalculateChecksum16(byte[] Buffer, UInt32 Offset, UInt32 Size)
        {
            UInt16 Checksum = 0;

            for (UInt32 i = Offset; i < (Offset + Size - 1); i += 2)
                Checksum += BitConverter.ToUInt16(Buffer, (int)i);

            return (UInt16)(0x10000 - Checksum);
        }

        private static UInt32[] CRC32Table = new UInt32[] {
            0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA, 0x076DC419, 0x706AF48F,
            0xE963A535, 0x9E6495A3, 0x0EDB8832, 0x79DCB8A4, 0xE0D5E91E, 0x97D2D988,
            0x09B64C2B, 0x7EB17CBD, 0xE7B82D07, 0x90BF1D91, 0x1DB71064, 0x6AB020F2,
            0xF3B97148, 0x84BE41DE, 0x1ADAD47D, 0x6DDDE4EB, 0xF4D4B551, 0x83D385C7,
            0x136C9856, 0x646BA8C0, 0xFD62F97A, 0x8A65C9EC, 0x14015C4F, 0x63066CD9,
            0xFA0F3D63, 0x8D080DF5, 0x3B6E20C8, 0x4C69105E, 0xD56041E4, 0xA2677172,
            0x3C03E4D1, 0x4B04D447, 0xD20D85FD, 0xA50AB56B, 0x35B5A8FA, 0x42B2986C,
            0xDBBBC9D6, 0xACBCF940, 0x32D86CE3, 0x45DF5C75, 0xDCD60DCF, 0xABD13D59,
            0x26D930AC, 0x51DE003A, 0xC8D75180, 0xBFD06116, 0x21B4F4B5, 0x56B3C423,
            0xCFBA9599, 0xB8BDA50F, 0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924,
            0x2F6F7C87, 0x58684C11, 0xC1611DAB, 0xB6662D3D, 0x76DC4190, 0x01DB7106,
            0x98D220BC, 0xEFD5102A, 0x71B18589, 0x06B6B51F, 0x9FBFE4A5, 0xE8B8D433,
            0x7807C9A2, 0x0F00F934, 0x9609A88E, 0xE10E9818, 0x7F6A0DBB, 0x086D3D2D,
            0x91646C97, 0xE6635C01, 0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E,
            0x6C0695ED, 0x1B01A57B, 0x8208F4C1, 0xF50FC457, 0x65B0D9C6, 0x12B7E950,
            0x8BBEB8EA, 0xFCB9887C, 0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3, 0xFBD44C65,
            0x4DB26158, 0x3AB551CE, 0xA3BC0074, 0xD4BB30E2, 0x4ADFA541, 0x3DD895D7,
            0xA4D1C46D, 0xD3D6F4FB, 0x4369E96A, 0x346ED9FC, 0xAD678846, 0xDA60B8D0,
            0x44042D73, 0x33031DE5, 0xAA0A4C5F, 0xDD0D7CC9, 0x5005713C, 0x270241AA,
            0xBE0B1010, 0xC90C2086, 0x5768B525, 0x206F85B3, 0xB966D409, 0xCE61E49F,
            0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4, 0x59B33D17, 0x2EB40D81,
            0xB7BD5C3B, 0xC0BA6CAD, 0xEDB88320, 0x9ABFB3B6, 0x03B6E20C, 0x74B1D29A,
            0xEAD54739, 0x9DD277AF, 0x04DB2615, 0x73DC1683, 0xE3630B12, 0x94643B84,
            0x0D6D6A3E, 0x7A6A5AA8, 0xE40ECF0B, 0x9309FF9D, 0x0A00AE27, 0x7D079EB1,
            0xF00F9344, 0x8708A3D2, 0x1E01F268, 0x6906C2FE, 0xF762575D, 0x806567CB,
            0x196C3671, 0x6E6B06E7, 0xFED41B76, 0x89D32BE0, 0x10DA7A5A, 0x67DD4ACC,
            0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5, 0xD6D6A3E8, 0xA1D1937E,
            0x38D8C2C4, 0x4FDFF252, 0xD1BB67F1, 0xA6BC5767, 0x3FB506DD, 0x48B2364B,
            0xD80D2BDA, 0xAF0A1B4C, 0x36034AF6, 0x41047A60, 0xDF60EFC3, 0xA867DF55,
            0x316E8EEF, 0x4669BE79, 0xCB61B38C, 0xBC66831A, 0x256FD2A0, 0x5268E236,
            0xCC0C7795, 0xBB0B4703, 0x220216B9, 0x5505262F, 0xC5BA3BBE, 0xB2BD0B28,
            0x2BB45A92, 0x5CB36A04, 0xC2D7FFA7, 0xB5D0CF31, 0x2CD99E8B, 0x5BDEAE1D,
            0x9B64C2B0, 0xEC63F226, 0x756AA39C, 0x026D930A, 0x9C0906A9, 0xEB0E363F,
            0x72076785, 0x05005713, 0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38,
            0x92D28E9B, 0xE5D5BE0D, 0x7CDCEFB7, 0x0BDBDF21, 0x86D3D2D4, 0xF1D4E242,
            0x68DDB3F8, 0x1FDA836E, 0x81BE16CD, 0xF6B9265B, 0x6FB077E1, 0x18B74777,
            0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C, 0x8F659EFF, 0xF862AE69,
            0x616BFFD3, 0x166CCF45, 0xA00AE278, 0xD70DD2EE, 0x4E048354, 0x3903B3C2,
            0xA7672661, 0xD06016F7, 0x4969474D, 0x3E6E77DB, 0xAED16A4A, 0xD9D65ADC,
            0x40DF0B66, 0x37D83BF0, 0xA9BCAE53, 0xDEBB9EC5, 0x47B2CF7F, 0x30B5FFE9,
            0xBDBDF21C, 0xCABAC28A, 0x53B39330, 0x24B4A3A6, 0xBAD03605, 0xCDD70693,
            0x54DE5729, 0x23D967BF, 0xB3667A2E, 0xC4614AB8, 0x5D681B02, 0x2A6F2B94,
            0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B, 0x2D02EF8D
        };

        internal static UInt32 CRC32(byte[] Input, UInt32 Offset, UInt32 Length)
        {
            if ((Input == null) || ((Offset + Length) > Input.Length))
                throw new ArgumentException();

            unchecked
            {
                uint crc = (uint)(((uint)0) ^ (-1));
                for (var i = Offset; i < (Offset + Length); i++)
                {
                    crc = (crc >> 8) ^ CRC32Table[ (crc ^ Input[i]) & 0xFF ];
                }
                crc = (uint)(crc ^ (-1));

                if (crc < 0)
                {
                    crc += (uint)4294967296;
                }

                return crc;
            }
        }
    }
}
